VSDs are the most common congenital heart disease (CHD), making up about 20 to 30 percent as an isolated lesion or more than 50 percent in conjunction with other cardiac anomalies of all the congenital cardiac lesions. Muscular VSDs, the type 4 of VSDs, is relatively uncommon and accounting for 5-12% of all the VSDs . “Swiss Cheese” VSDs is a subtype of muscular VSDs and most serious form, which is the result of non-contraction of ventricular septum during embryonic development . As conventional surgical repair of “Swiss cheese” VSDs is generally accompanied by substantial early and late mortality and morbidity (8.5-25%) , much higher than that of other VSDs, it is important to treat “Swiss cheese” VSDs as one kind of very complex CHDs but not common VSDs and should attract much more attention of the pediatricians.
Historically, pulmonary artery banding was the preferred treatment of “Swiss cheese” VSDs in most of the patients. The aim is to protect the pulmonary vascular bed and relieves heart failure and win more time for further treatment, biventricular repair or palliative cavopulmonary connection [6, 9]. However, as pulmonary artery banding may lead to various complications afterwards, such as right ventricular hypertrophy, right ventricular outflow tract obstruction distortion of the pulmonary artery and inadequate protection of the pulmonary vascular bed, this technique may be only appropriate in selected patients who are sufficiently ill and cannot reasonably be expected to tolerate CPB.
With improvement of surgical techniques and perioperative management in the past several decades, a growing number of surgeons prefered single-stage repair but developed different opinions and surgical techniques including direct closure through ventriculotomy, sandwich patch technique or hybrid closure. However, each author has been successful with his/her technique, yet no technique is uniformly reproducible. Short and long term complications are still the cornerstones of the surgical results , and pediatric cardiac surgeons are still challenged by the tough treatments of “Swiss cheese” VSDs . Therefore, they have been seeking more ideal techniques for the treatment of this complex VSD. In 2006, Alsoufi and his colleagues  reported a new approach, the transatrial re-endocardialization of interventricular septum, to treat “Swiss cheese” VSDs. Although the outcome has been improved with low incidence of permanent heart block, this technique has not been widely used because of its technical difficulty and long CPB and procedure time.
The technique of using a large patch extending on to the right ventricular free wall and exclusion of part of the right ventricular apex provided a simple solution in the last several decades. Macé L and his colleagues  modified this technique with intermediate fixings to avoid septal bulging induced cardiac dysfunction. They applied this modified single patch technique in 5 cases with promising short term results. However, long term in adult life, the reduced size of right ventricle, and diastolic dysfunction cause problem, such as cyanosis, right heart failure, cirrhosis, arrhythmia . The reason may be related to the fact that in most of the cases, the material of the patches being used to close the defects were Dacron and did not have growth potential. Furthermore, the patch was too large and it might cover the entire endocardium of the right ventricle. These would not only limit the development of the right ventricle, but also lead to diffuse fibrosis and calcification of the right ventricular endocardium years later. Right ventricular dysfunction would be the results, and then the increasing pressure in the right heart, that could cause right atrium dilation, reopening of the foramen ovale induced cyanosis and arrhythmia.
In 2014, we developed a modified strategy to treat “Swiss cheese” VSDs to address the potential drawbacks of previously reported single patch technique but based on the same technical principle of exclusion of the right ventricular apex. We tried to use two fresh pericardium patches to close the defects during the procedure instead of a large prosthetic patch, like Darcon or Gore-tex. The main technical points were described above in the procedure part. Our technique is suitable for infants over 3 months old. Although the CPB time (96 min) and aortic clamping time (68 min) in our series of cases are longer than that of previous reported research , if we take a look at the median time for exposing and closing of “Swiss Cheese” VSDs, 56 min is relatively short and the advantages of our technique can be easily recognized in terms of technical requirements and operation time. However, it is pretty hard to apply this technique in patients under 3 months old as a full view exposure of the VSDs is almost impossible. If the patient's condition is too critical to wait for receiving this technique till 3 months old, pulmonary artery banding can be performed in advance. In this group, one case was taken according to this strategy, and finally had a biventricular repair with good result. The fact that there were no serious complication in the early postoperative period in this study indicates that this technique is safe and reliable. There was no serious complication during a median follow-up period of 3.2 years. Follow-up TTE test showed normal systolic and diastolic cardiac function in all the 10 cases. This may be related to the use of fresh pericardial patches, as it was reported that fresh autologous pericardium showed good biological characteristics, such as free of retraction, thickening, stiffness, fibrosis and calcification , thus it possibly does not affect right ventricular function in midterm period. In addition, the two-patch technique not only protects the moderator band, an important anatomical structure of the right ventricle, but also avoids a too large patch to cover the entire inner right ventricular wall and thus limiting the diastolic function of the right ventricle.